Dynamo-electric machines



March 29, 1966 .1. ruDGE ETAL 3,243,516

I DYNAMO-ELECTRIC MACHINES Filed July 2z, 196s s sheets-sheet 1 March29, 1966 J. TUDGE ETAL DYNAMIC-ELECTRIC MACHINES Filed July 22. 1963 6Sheets-Sheet 2 March 29, 1.966 J. TUDGE ETAL 3,243,515

, DYNAMO-ELECTRIC MACHINES Filed July 22. 196s e sheets-sheet s l March29, 1966 J. TUDGE ETAL DYNAMIC-'ELECTRIC MACHINES 6 Sheets-Sheet 4.

Filed July 22, 1963 March 29, 1966 .1. TUDGE ETAL DYNAMO-ELECTRICMACHINES Filed July 22, 1963 6 Sheets-Sheet 5 AMau-ch 29, 1966 J. TUDGEETAL.

DYNAMo-ELEGTRIC MACHINES 6 Sheets-Sheet 6 Filed July 22. l196s UnitedStates Patent 3,243,616 DYNAMO-ELECTRIC MACHINES Joseph Tudge,Manchester, and Istvan Csillag, Sale, England, assignors to AssociatedElectrical Industries Limited, London, England, a British company FiledJuly 22, 1963, Ser. No. 296,777 Claims priority, application GreatBritain, July 24, 1962, 28,464/ 62 2 Claims. (Cl. S10-54) This inventionrelates to dynamo electric machines and morev .particularly t-o therotors of turbo alternators.

One of the chief limitations in producing tur-bo alternators havingratings exceeding 500 mw. without substantially increasing the weight isthe temperature of the rotor copper winding. Hitherto, it has been thepractice to circulate hydrogen at elevated pressures in direct contactwith the -rotor windings. It is also well known to cool stator windings-by circulating a liquid, such as water, through hollow conduct-ors.However, in the case of a rotor one of the difiiculties which exists isto limit the D.C. leakage currents which exist in the water columns orducts feeding the conductors. Furthermore, in order to reduce thefriction head and limit the temperature rise of the water, it isnecessary that the water should only flow Y through the conductors for ashort distance.

The main object of the invention is to provide an improved arrangementwhich substantially satises these requirements.

According to the present invention an electrical turbo alternator has `arotor, a hollow shaft, a lianged end t said shaft secured axially tosaid rotor so as to support it, conductors forming a rotor winding,surfaces defining longitudinal passages through said conductors, meansfor passing cooling fluid through said conductors including a ductextending longitudinally through the interior of said shaft, atransverse .plate within the flanged end of said shaft secured to therotor end and supporting the duct and fluid connections between saidsupply duct and the conductor passageways.

Each of the input inlet manifolds may be connected to a liquid supplyduct extending through the rotor shaft and similarly each of the outputmanifolds may be connected to a liquid discharge duct a-lso extendingthrough the rotor shaft.

The transposition of the rotor conductors may be in the manner employedin so-called Roebel stator bars.

In such an arrangement the conductors are arranged in the slot in twostack-s side by side, the conductors in one stack slope downwards to abottom position, then bend sideways so as to transfer to the other stackand then slope upwards, each of the conductors in turn occupies thebottom position in the slot but at diiferent locations along the slot.

The above description .refers for simplification to a slot on top of therotor so that the top conductor is radially outermost and the bottomconductor radially innermost.

The manifolds are preferably in sub-slots underneath (i.e. radiallyinside of the conductor slots). Alternatively, they could extend betweenthe conductor slots.

In order that the invention may be more clearly understood referencewill now be made to the accompanying drawings in which:

FIG. 1 is a longitudinal section of one end of a rotor showing theliquid supply and discharge connections.

FIG. la is a longitudinal section through a slot and is a section onIII-III of FIG. 1b.

FIG. 1b is a plan view of the conductors in a slot showing thetransposition,

FIG. 1c is a cut-away perspective View of the hose forming a manifold.

ICC

FIG. 2 is a cross sectional view on the line II-II of FIG. 1 showing theconnections between. the shaft supply and discharge ducts of thecorresponding sub-slots.

FIG. 3 is a diagrammatic view showing how the coils would be arrangedelectrically.

- FIG. 4 is an enlarged cross sectional view of a slot taken on the lineIV-I-V of FIG, 1b.

FIG. 5 is a similar view taken on the line V-V of FIG..1b.

FIG. 6 is a cross sectional view of the discharge volute.

FIG. 7 is a brazed joint with tubular coupler.

FIG, 8 is a longitudinal section of part of an alternator rotor showinga modified' construction.

FIG. 9 is a section on the line VI-VI of FIG. 8.

Referring irst to FIG. l the reference 101 indicates the core of a turboalternator mountedy on a hollowshaft 2. Water liows from an overheattank (not shown) through a stationary supply pipe 1 extending throughthe end of the rotor shaft 2, the outer surface of the duct is threadedat 3 to act as a screw pump to enable the highest possible head to beapplied in chamber 4 without excessive leakage back through the annulusbetween this stationary shaft and the rotating member. Whilst this is apreferred shaft seal', other suitable shaft seals could be used;however, a method which does not involve rubbing seals with possibilityof wear would be desirable.

The water then flows from the chamber 4 through two diametricallyopposite radial inlet pipes 5 into diametrically opposite inletquadrants 6 of an annulus. From the inlet quadrants of the annulus thewater is distributed to each inlet coil side by way of manifolds formedby insulation hoses 7 in inlet sub-slots 8. The arrangement of radial'pipes and annulus is shown more clearly in FIG. 2 and the water circuitto the coils is shown in FIG. 3.

Frorn FIG. 3, and also FIG. l, it will be seen that hoses forming theImanifolds extend from the annulus throughout the length of the sub-slotsproviding communication with each conductor 9 at the cross-overs at thebottom of the coil, the conductors being transposed in each slot in amanner which will be described subsequently. All adjacent coil sidesassociated with one pole are inlets as far asy the water is concernedand are connected to one of the inlet quadrants of the annulus and alldiametrically opposite (electrically) coil sides are also inlets.

FIG. 3, which is an explanatory winding diagram, shows three coils onlyassociated with one pole, and for simplicity and ease of tracing thecircuit, each coil has only six turns, three turns deep by two stackswide, whereas FIG. l, and the `slot sections shown in FIGS. 4 and 5,have sixteen turns, eight deep by two wide. In FIG. 3, the full linesrepresent the hollow conductors in that stack nearest the pole axis inthe case of each coil, and the dotted lines represent the other stack.In FIG. 3 the water inlet tappings at the bottom cross-overs of theinlet coil sides are indicated by capital letters A-M and thecorresponding outlets are indicated by small letters, By tracing throughthe circuit it will be noticed that each inlet feeds two paths each witha separate half outlet in the other coil side each at adjacentcross-overs. Thus, the inlet B is connected. through the path indicatedin full line with the outlet bc and through the path indicated 'indotted line with the outlet ab. The two parallel paths taken by thewater are, therefore, of slightly different lengths equivalent to thepitch of the cross-overs, but this is `so short compared with the lengthof the path-which is about half a turn-as to be of no consequence asregards the temperature rise of the water.

It will be noticed from FIG. 3 that the middle coil has :opposite handedcross-overs. The reason for this will be 'appreciated after tracing outthe water circuit for the smallest coil when it will be noticed that thehalf outlet g is the half discharge from tapping G on the next coil,[and likewise, with half outlets. If now all the cross-overs were of thesame hand g would receive water from inlet L giving a path length and,therefore, a water temperature rise for that one particular path abouttwice that of the other paths. Handling each alternate coil oppositelyproduces substantially equal path lengths throughout the winding, thispath length being half a turn and is equivalent to a single passcooling7 system where water enters one end of the machine and. isdischarged from the other after passing through all conductors inparallel, yet a multiplicity of hose connections in the end winding,which would be impossible to accommodate and some of which would Vbesubject to the very high pressures in the outer turns, is completelyavoided.

This construction also permits a bench-assembly of each half-coil alongwith the hoses forming the supply or discharge manifold and groundinsulation. Each cornplete half-coil can be inserted into the windingslots, as shown in FIGS. la, 1b, 4 and 5, and the conductors joined onthe end windings electrically and hydraulically as shown in FIG. 7 bymeans of brazed tubular couplers.

After its passage from one half-coil into the other halfcoil, the wateris discharged again from the bottom crossovers into a similar dischargemanifold formed by a hose lying in the sub-slot and thence to thedischarge quadrants 10 of the annulus. The supply and dischargequadrants are separated by partitions 11. From the annulus the water owsthrough radial discharge pipes 12into a discharge annulus 13 concentricwith the supply pipe 1 and along the shaft to the volute 14, a sectionof which is shown in FIG. 6, there to be discharged into a tank belowthe rotor level from which it is pumped back into the overhead tank byan external pump.

The head, for this arrangement, to force water through the windingswithout producing negative pressures, is that developed by rotation ofthe rotor between the radius of the discharge annulus 13 and the radiusof inlet chamber 4 together with ther initial pressure in chamber 4which can be supplied from the overhead tank, and resisted by the screwpump action of inlet pipe 1. Higher pressures would be available if apositive seal were used where the water enters the shaft but this wouldinvolve the problem of seal wear.

Comparing FIGS. 1 and 2 it will be observed that the ducts 5 and 12 areboth shown in a vertical plane in FIG. 1 whereas actually they aredisplaced rotationally through 90, as s shown in FIG. 2.

The construction of the insulation hoses for the manifolds is shown inFIGS. la and lc. The hose has towithstand the pressure existing at theradius of the sub-slot which may be in the order of 1,000 p.s.i. atnormal speed possibly 1,500 p.s.i. at overspeed. The hose materialshould rstly be impervious to water and. have exibility to give underthermal expansion of the winding. A suitable material is P.T.F.E.(polytetrafluoroethylene) as indicated by the reference 15 but it willbe necessary to have external metal reinforcing ferrules 16 separated bynarrow but strong insulation ferrules 17. Secondly, the hose willrequire internal reinforcing bushes 18 to prevent collapse due torotation should the rotor at some stage run without water at elevatedtemperatures. These bushes must be of strong insulation having waterimpervious properties. A suitable material is P.C.T.F.E.(polychlorotrifluoroethylene) and the ends of the bushes and ferrulescan be chamfered to give the complete hose some flexibility. Thirdly,although the design has been arranged to accommodate long hoses toreduce leakage currents particularly those between the winding and theannulus formed by quadrants 6 and 10, some of which have half the rotorvoltage across their ends, it may be necessary to provide an extensionto the end of the insert 7 which will act as a guard ring againstcorrosion of the effective part of the insert under the crimping ferrule15. A suitable material for these inserts, to reduce the extent ofelectrolytic attack, would be stainless` steel.

The electrical leads to the collector 20 (FIG. 1) could be of theconventional kind passing through holes in the solid section of theshaft, in which case water discharging from point a at the beginning ofthe electrical circuit could be conveyed to an outlet chamber 10 of theannulus through aninsulating hose, and the water entering the end of theelectrical circuit at a point similar to S (FIG. 3) could be deliveredalso through a hose from an inlet quadrant 6 of the annulus.Alternatively, the leads to the collector could be of hollowconstruction and watercooled by making appropriate water connections atthe collector end of the leads. Water-cooled leads would also apply ifthe collector is of the mercury -contact type or whether the exciter isof the A.C. type having rotating rectiers mounted on the shaft. Thesolid or Water-cooled leads could occupy the space, if it is so desired,of the cylindrical packer 22.

The water pipes conveying water to annulus inlet quadrants 6 and theannulus itself is insulated from the rotor shaft to permit insulationresistance measurement of the rotor main ground insulation 23 to betaken without completely draining the water.

The above describes a direct water-cooled rotor having the equivalent ofa single pass system, the Water being discharged after its passagethrough each half turn. On rotors of intermediate rating it -rnay onlybe necessary to discharge the water after its passage through onecomplete coil in which case the conductors would not requiretransposition. The turns could progress up one stack, crossing over tothe adjacent stack on the end windings, and back to the lbottom whereanother cross-over can be made to the -coil in the next slot. Hoseconnections for water can then be made at these bottom cross-overs inthe end winding where the press-ure is least. A further alternative isto have one stack only of conductors in each slot 15, the turnsprogressing up one slot crossing over at the top to the adjacent slotand back to the bottom where Water hose connections can be made, againwhen the pressure is least. Intermediate water tap-pings could be madepart way up the slot on small diameter rotors providing the pressure isnot excessive for the hose.

As is sho-wn more clearly in FIGS. la and 1b the conductors in the nearstack shown in the left slope upwardly from left to right when theyreach the uppermost posi-y tion, e.g. at 24, they are bent horizontallyinto the further stack and then slope downwardly. Similarly, as eachconductor in the further stack reaches the bottom of the slot it will bebent horizontally into the near stack. Thus, there is a progressivetransposition of the conductors in the slot each successively reachingthe bottom position.

FIG. 4 is a section through a transposition point such as at the sectionline IV--IV of FIG. 1b in which the conductor 25 is consequently in themid position in the slot 125. The longitudinal conductor passage 26 iscoupled with the manifold 27 through the port 8.

28 are spacer blocks on opposite sides of the conductor 24. At the topof the slot a conductor 29 is similarly undergoing transposition but inthe opposite direction to the conductor 25 and is held in position byspacer blocks 30. The reference 31 represents the usual Wedge holdingthe conductors in the slot.

FIG. 5 shows a similar view but on the section line V-V of FIG. 1b whichis in between the transposition points. Thus, there is no connectionbetween the passages 26 and the manifold. Spacer blocks 32 are insertedat the top and bottom of the slot.

The construction shown permits a bench-assembly of each half-coiltogether with its hoses and earth insulation. Each complete half-coilcan be inserted into the winding slots and the conductors joinedelectrically and hydraulically as shown in FIG. 7 by means of brazedtubular couplers 33 inserted over the reduced ends of the conductors 25.n

In FIG. 8 the rotor core 101 has an integral llangc 102 which carries aretaining ring 103. This retaining ring supports the end-winding 104against centrifugal force. A hollow shaft 105 is bolted to the flange102. In a recessed chamber in the hollow shaft 105 is a transmissionplate 106 attached by bolts 125 to an insulating adaptor 124 which inturn is -bolted to the rotor body. The adaptor serves to insulate thedisc 106 from the rotor core 101. Radial passages 107, which are sealedby plugs 116 at their radially outermost ends, convey liquid from thesupply passage 108 in the rotor shaft (which corresponds to duct 4 ofFIG. 1) to the ends 112 of the inlet manifolds. Similarly passages 110convey liquid from the ends of the outlet manifolds to a discharge`passage 111 in the rotor shaft. This can be seen more clearly in FIG.9. The ends 112 of the manifolds are located in holes 114 in the disc106, and a distance piece 115 is provided to make up for inaccuracies infitting. The required thickness of the distance piece is ascertainedduring assembly. Guide vanes may be provided underneath the plug 116 toassist the ow of liquid.

The electrical leads 117 pass under the winding and through holes 118 inthe disc 106 and corresponding holes in the ange of the hollow shaft Sinto a pocket 119 which is packed with insulation. In this pocket ajoint 120 is made to the lead 121 which passes to the collector. Thejoint 120 and its insulation are held in place by ring 122 and disc 123.

What We claim is:

1. In an electrical turbo alternator, a rotor, a hollow shaft, a flangedend to said shaft secured axially to said rotor so as to lsupport it,conductors forming a rotor winding, surfaces defining longitudinalpassages through `said conductors, means for passing cooling uid throughsaid conductors including ducting extending longitudinally through theinterior of said shaft, a transverse plate within the flanged end ofsaid shaft secured to the rotor end and electrically insulated therefromand supporting the ducting and fluid connections through said platebetween said shaft ducting and the conductor passageways.

2. In an electrical turbo alternator, a rotor, a hollow shaft, a flangedend to said shaft secured axially to said rotor so as to support it,condu-ctors forming a rotor winding, surfaces defining longitudinalpassages through said conductors, means for passing cooling fluidthrough said conductors including concentric inlet and outlet ductsextending longitudinally through the interior of said shaft, atransverse plate within the flanged end of said shaft secured to therotor end and electrically insulated therefrom and supporting the ductand uid connections between the supply duct and the conductorpassageways on diametrically opposite quadrants in the rotor crosssection and fluid connections between the conductor passageways in theintervening quadrants and said outlet duct.

References Cited by the Examiner

1. IN AN ELECTRICAL TURBO ALTERNATOR, A ROTOR, A HOLLOW SHAFT, A FLANGEDEND TO SAID SHAFT SECURED AXIALLY TO SAID ROTOR SO AS TO SUPPORT IT,CONDUCTORS FORMING A ROTOR WINDING, SURFACES DEFINING LONGITUDINALPASSAGES THROUGH SAID CONDUCTORS, MEANS FOR PASSING COOLING FLUIDTHROUGH SAID CONDUCTORS INCLUDING DUCTING EXTENDING LONGITUDINALLYTHROUGH THE INTERIOR OF SAID SHAFT, A TRANSVERSE PLATE WITHIN THEFLANGED END OF SAID SHAFT SECURED TO THE ROTOR END AND ELECTRICALLYINSULATED THEREFROM AND SUPPORTING THE DUCTING AND FLUID CONNECTIONSTHROUGH SAID PLATE BETWEEN SAID SHAFT DUCTING AND THE CONDUCTORPASSAGEWAYS.